pzozulka
asked on
Subnets and VLANs
I'm don't understand subnets and VLANs 100%, so I need a little bit of help. In the example below, the only thing that changed is the subnet mask on my WIN 7 PC.
My computer had the static IP settings below:
IP address: 10.0.64.4
Subnet: 255.255.255.0
Gateway: 10.0.64.1
DNS: 10.0.32.3
CAN ping anything in my own subnet/VLAN: DHCP scope=10.0.64.0, VLAN 640, range=10.0.64.3-14, router 10.0.64.1, subnet=255.255.255.240
CAN ping anything in: DHCP scope=10.0.24.0, VLAN 240, range=10.0.24.3 - 30, router = 10.0.24.1, subnet=255.255.255.224
CANNOT ping anything in: DHCP scope= 10.0.64.16, VLAN 642, range=10.0.64.19 - 30, router=10.0.64.17, subnet=255.255.255.240
CANNOT ping anything in: DHCP scope=10.0.64.32, VLAN 644, range=10.0.64.35-38, router=10.0.64.33, subnet=255.255.255.248
HOWEVER, when I changed my settings to allow DHCP to automatically get an IP, I had the settings below:
IP: 10.0.64.4
Subnet: 255.255.255.240
Gateway: 10.0.64.1
DNS: 10.0.32.3
With these settings I was able to ping ALL subnets/VLANs. The only thing that changed is the subnet mask. Why am I now able to (all of sudden) ping all IPs.
My computer had the static IP settings below:
IP address: 10.0.64.4
Subnet: 255.255.255.0
Gateway: 10.0.64.1
DNS: 10.0.32.3
CAN ping anything in my own subnet/VLAN: DHCP scope=10.0.64.0, VLAN 640, range=10.0.64.3-14, router 10.0.64.1, subnet=255.255.255.240
CAN ping anything in: DHCP scope=10.0.24.0, VLAN 240, range=10.0.24.3 - 30, router = 10.0.24.1, subnet=255.255.255.224
CANNOT ping anything in: DHCP scope= 10.0.64.16, VLAN 642, range=10.0.64.19 - 30, router=10.0.64.17, subnet=255.255.255.240
CANNOT ping anything in: DHCP scope=10.0.64.32, VLAN 644, range=10.0.64.35-38, router=10.0.64.33, subnet=255.255.255.248
HOWEVER, when I changed my settings to allow DHCP to automatically get an IP, I had the settings below:
IP: 10.0.64.4
Subnet: 255.255.255.240
Gateway: 10.0.64.1
DNS: 10.0.32.3
With these settings I was able to ping ALL subnets/VLANs. The only thing that changed is the subnet mask. Why am I now able to (all of sudden) ping all IPs.
ASKER
CANNOT ping anything in: DHCP scope= 10.0.64.16, VLAN 642, range=10.0.64.19 - 30, router=10.0.64.17, subnet=255.255.255.240
That's expected too. You PC thinks those addresses are local. The problem is they're actually on different networks.
OK so I understand that when i'm on a different network than another PC, it forwards packets to the default gateway, and the routers work things out.
However, when i'm on 10.0.64.0/24 network, I should be able to communicate with all PCs in the range of 10.0.64.1 - 254. So when a PC comes along with IP 10.0.64.25, it does fall into my IP range, and I should be able to ping it. I still don't understand why I am not able to.
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
ASKER
I think your last post was cut off.
No. I was thinking of an analogy but it didn't jell. :-(
ASKER
:) sounds good. It made sense either way.
This means your computer thinks that it is on the 10.0.64.0/24 network. Which means that it expects that it is on the same network/broadcast domain/VLAN with devices that have IP addresses 10.0.64.1-254.
Yep. Those device are within the range of addresses that your computer expects to see on it's network.
That's expected too. Those devices are seen as being on different networks so your PC will forward that traffic to the default-gateway which then routes the packets to the correct network.
That's expected too. You PC thinks those addresses are local. The problem is they're actually on different networks.
Same as previous.
Now you are on the 10.0.64.0/28 network. Your PC thinks the only thing that's local is 10.0.64.1-14. Because it knows the 10.0.64.17 and higher addresses aren't local, it forwards those packets to the default-gateway.
Basically, when you had an address of 10.0.64.4/24, you had the incorrect mask.